The present invention relates to telecommunications and telephonic devices, and more specifically to the use of telecommunications devices by wearers of hearing aids.
Millions of Americans suffer from hearing loss. Most commonly, hearing loss is of one of four types. In slope loss, the ability to hear high frequencies is lost while the ability to hear sounds in the low frequencies is retained. In reverse slope loss, the ability to hear low frequencies is lost while the ability to hear sounds in the high frequencies is retained. Less frequently, the hearer loses the ability to hear sounds in all normally audible frequencies. Finally, some people lose the ability to hear in only a small range of frequencies.
Typically, someone who suffers from hearing loss wears a hearing aid. Hearing aids are electroacoustical devices worn to compensate for a hearing impairment by amplifying sound. They include aids placed behind the ear, aids placed in the ear, and aids placed in the external auditory canal. Hearing aids generally consist of a microphone, an amplifier, and a speaker, but are increasingly sophisticated instruments. Many have automatic gain control and digital signal processing; they can often be programmed to remedy a specific pattern of frequency loss specified by a user""s prescription. Hearing aids utilize analog or digital circuitry. Most hearing aids in use today are analog.
Programmable hearing aids include amplifiers and filters controlled by an external digital source. Typically, such a hearing aid will include a memory module and a microprocessor to access the memory locations and to control the frequency response.
Gain is a measure of amplification. The acoustic gain of a hearing aid is the difference in dB between the output and the input at a particular frequency. Frequency response specifies hearing aid gain as a function of frequency when the volume control is in the normal operating range. Circuits that automatically change the gain or frequency response in response to changes in the input signal are called automatic signal processing (ASP). In hearing aids, most types of ASP modify only the gain.
Although hearing aids are of particular use in conversations and other face-to-face situations, they are less useful when combined with signals from electronic device, such as a wireless telephone. Feedback, distortion and radio frequency (RF) interference often interfere with a wearer""s hearing aid. Some hearing aid wearers report interference from simply walking past a wireless device in use. As the use of wireless communications devices proliferates, this problem is becoming more and more serious.
What is needed is an invention that allows hearing aid wearers to use electronic and telecommunications devices, such as wireless telephones, without interference and while enabling them to compensate for their frequency loss.
The present invention includes an apparatus and method which allow a hearing aid to be integrated into a sound-producing device. Sound-producing devices compatible with the invention include wireless communications devices such as cellular telephones. In such uses, the hearing aid can be integrated with the earpiece, such as a headset or a handset. A programmable hearing aid can be programmed to compensate for the wearer""s specific hearing loss. The mounting of the hearing aid is accomplished so that RF interference in the hearing aid output is avoided compared with conventional systems.
Copending application Ser. No. 08/639,651, incorporated herein by reference, describes an approach to decreasing interference between hearing aids and wireless communications devices. Application Ser. No. 08/639,651 concerns the use of ferrite materials in a flexible matrix to create an RF shadow that effectively avoids interference. This application applies the teachings of that application but also develops new approaches to reducing interference.